Interpreting Fracture Energy in Granular Particle Crushing Using Acoustic Emission for Real-Time NDT Monitoring

Particle crushing is a fundamental process influencing the strength, deformation, and permeability of granular soils, with critical implications for the performance and long-term stability of underground foundations and earthwork backfills. Conventional methods for assessing particle breakage, such as particle size distribution (PSD) analysis, are inherently destructive and unsuitable for continuous or in situ monitoring. To address this limitation, this study investigated the application of acoustic emission (AE) sensing as a non-destructive technique for capturing grain crushing processes during testing by interpreting associated fracture energy under one-dimensional (1D) compression.

Laboratory experiments were conducted using single soil particles and two-dimensional chalk rod specimens subjected to controlled 1D compression. Real-time AE monitoring was employed to capture micro-mechanical fracture events, with a focus on analysing signal parameters such as cumulative AE signal strength. By correlating these AE metrics with mechanical responses and known particle breakage behaviours, a model was developed to interpret fracture energy directly from AE signal characteristics.

This approach enables a novel pathway for estimating the fracture energy during particle crushing, which can be further linked to evolving breakage indices and changes in particle size distribution. The proposed model has potential applications in real-time assessment of density changes in subsurface soils or backfills, particularly in buried infrastructure networks where invasive sampling is impractical. The findings advance the development of performance-based, non-destructive geotechnical monitoring frameworks for long-term soil stability evaluation.